Hamed Azimi; Majeid Heydari; Saeid Shabanlou
Abstract
Dam break is an important phenomenon which significantly affects the environment as well as the inhabitants of the downstream areas of the dam. In the present study, the hydraulic break of Malpasset dam as a result of sudden flooding was simulated numerically using the FLOW-3D software. The two-equation ...
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Dam break is an important phenomenon which significantly affects the environment as well as the inhabitants of the downstream areas of the dam. In the present study, the hydraulic break of Malpasset dam as a result of sudden flooding was simulated numerically using the FLOW-3D software. The two-equation k-ε turbulence models and RNG k-ε turbulence model were used to simulate the flow field turbulence. Also, the free-surface variations of the flow were simulated using the VOF (Volume of Fluid) scheme. The results obtained from the numerical model were in good agreement with those predicted by the EDF model. Based on the simulation results, the maximum pressure occurred at the lower layers of the flow and reduced as the free surface of the flow was approached. The maximum pressure increased at each point in time. The maximum longitudinal velocity occurred at the front of the advancing wave resulting from break of the dam, and subsequently decreased due to the increasing depth at the downstream of the dam. Additionally, the effects of obstacles with different shapes on the flow pattern arising from dam break (due to sudden flooding) were also investigated. Examination of these effects revealed that the cubic obstacle placed obliquely in the flow direction produced the maximum separation region at its downstream. Conversely, this separation region was eliminated completely when a cylindrical obstacle was used. The maximum and minimum Froude numbers were obtained for the flow encountering the perpendicular cubic obstacle and the flow impacting the cylindrical obstacle, respectively.
Azam Akhbari; Amir Hossein Zaji; Hamed Azimi; Mohsen Vafaeifard
Abstract
Weirs are installed on open channels to adjust and measure the flow. Also, discharge coefficient is considered as the most important hydraulic parameter of a weir. In this study, using the Radial Base Neural Networks (RBNN) and M5' methods, the discharge coefficient of triangular plan form weirs is modeled. ...
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Weirs are installed on open channels to adjust and measure the flow. Also, discharge coefficient is considered as the most important hydraulic parameter of a weir. In this study, using the Radial Base Neural Networks (RBNN) and M5' methods, the discharge coefficient of triangular plan form weirs is modeled. At first, the effective parameters in the prediction of the discharge coefficient are identified. Then, by combining the input parameters, for each of the RBNN and M5' methods, six different models are introduced. By analyzing the modeling results for all models, it was shown that the M5' model is capable of modeling the discharge coefficient more accurately. Also, based on the modeling results, a model that considered the impact of all input parameters was introduced as a superior model. The mean absolute percentage error (MAPE) and correlation coefficients (R2) values for the preferred model in the test mode were calculated 2.774 and 0.831, respectively. Also, for each of the M5' models, some relationships were proposed to estimate the triangular plan form weirs. The evaluation of these relationships showed that the parameters of the ratio of head over the weir to channel width (h/B) and Froude number (Fr) were the most effective parameters in the prediction of the discharge coefficient.
